On occasion, a tractor may not have enough weight to provide sufficient traction to tow trailers containing heavy, harvested crops. For example, the trailers may weigh twice as much as the tractor making it difficult for the weight of the tractor to provide sufficient traction, resulting in slippage of the tractor's wheels. Further, under adverse weather conditions, the tractor may experience even greater slippage because of wet soil or mud. To take advantage of the trailer's weight, a tractor can be mechanically coupled to a drive axle of a trailer. As a result, the tractor's power drives the trailer and the weight of the trailer and the harvested crop enhance the traction at the driven wheels of the trailer.